Bascule bridge



T. E. BROWN, JR.

Patented Feb. 14, 1922.

2 SHEETS-SHEET l.

INVENTOR T. E. BROWN, JR-

' BASCULE BRIDGE.

APPLICATION men FEB. 12, 1920.

Patented Feb. 14, 1922.

2 $HEETSSHEET 2.

lNVENTOR 7424M 5 My UNITED STATES PATENT OFFICE.

BASGULE BRIDGE.

Specification of Letters latent. P315911 ted Feb. 14, 1922.

Application filed February 12, 1920. Serial No. 358,075.

To aZZw limit it may concern Be it known that I. THOMAS E. Bnowru J12, a citizen of the United States, and a resident of Morristowm in the county of Morris and State of New Jersey,- have invented certain new and useful Improvements in Bascule Bridges, of which the following is a specification.

This invention relates to improvements in bascule bridges of the class in which the balance of the moving span is attained by means of counterweights pivotally attached to the rearwardly extended end of the span.

In the usual constructions of this class the counterweight is pivotally hung from the rearwardly extended end of the moving span, i. e. that part of the moving span which extends rearwardly beyond the point rotation. Cases frequently arise in which the height of the bridge floor above the water is insufiicient to admit of the counterweights' being placed below the bridge floor without the use of expensive watertight pits, and in these cases to avoid such pits. it is necessary to place the counterweights above the heel of the span and it is obvious that when so placed they must be at a suiiicient height above the floor of the bridge to avoid obstruction of the roadway when the bridge is in its closed position.

When the counterweight is suspended from the end of the span, its center of gravity being below the support, it is in stable equilibrium, but when it is placed with its center of gravity above its supporting pivot obviously it is then in unstable equilibrium and meansmust be provided to prevent its falling over.

Heretofore the means used to stabilize or prevent the counterweight from falling over has consisted of fixed towers frames and the like with links, guides or guys to the counterweight and it is a principal object of my invention to stabilize the counterweight without the use of such fixed towers or frames.

Another ob ect of my invention is to so j construct and arrange the stabilizing de vices that the span will be balanced in all its positions, and still another object is a construction which will limit the upward movement of the span.

I accomplish these objects by a movable beam pivotally connected to the rearwardly extended end of the moving span and guided at its other end by a track and by a counterweight supported by the beam and the span by means of two members, the one pivotally connected to the moving span the other pivotallv connected to the beam, both of these members being pivotally connected together and further by suitably choosing the positions of the pivots and suitably shaping the track.

Referring to the drawings:

Fig. 1 is a side view of a bridge incorporating the preferred form of my invention.

Fig. 2 is a cross-section on line c .'a of Fig. 3 is a view through pier A of Fig. 1 showing an end view of the roller and tracks.

Fig. 4t is a view of an alternative construction which may be used in place of the rollers shown in Fig. 3.

Fig. 5 shows my invention applied to a bridge of the rolling type.

Figs. 6 and 7 show modified forms of my invention. i I

Similar reference numerals refer to 'simlar parts in all the figures. Parts of the fixed structure tending to'obscure the clearness of figures.

Referring to 1, B is the moving span of a bascule bridge, P the pivot or trunnion about which it revolves. A, A and A are piers. and D a portion of the fixed structure supporting said pivot P. F and F are portions of the fixed approach spans.

W is a counterweight supported on a mem her or post 1 which is pivotally connected to the heel or rearwardlv projecting end of the moving span B by the pivot 2.

C is a beam attached to the rearwardly extended end of the span B by the pivot 6. The rearward end of the said beam C is sup ported on the axle 10 of wheels or rollers 11, said rollers 11 being free to move forward or backward on the track T as the bridge opens and closes. 13 are hold-down tracks to prevent lifting of the rollers off of the track T. The construction of these hold-down tracks is more clearly shown in the sectional viewEi 3. For clarity of the drawing in Fig. 1 tie nearer of these tracks 13 has been omitted in that figure. 8 is a post or strut member pivotally connected by pivot 7 to the member 1 supporting the counterweight W and to the beam O'by pivot 9. c. g. is the the drawings are omitted from the position of the center of gravity ofthe span B, and G is the center of gravity of the counterweight W.

The bridge may be operated in any usual manner as by gear segment 3, secured to the moving span, and meshing with pinion t on a shaft 5, supported on afixed part of the structure. Shaft 5 may be rotated by any suitable gearing and power.

It will be understood that the description refers to one side of the bridgelonly and that the parts described will in general be duplicated on the other side of the bridge.

The counterweight 1V may be constructed in a single unit as shown in Fig. 2, with connections to the trusses or girders on each side of the bridge or may be in separate units one on each side of the bridge if desired.

When the toe end of bridge B rises and the heel of bridge B and the beam C de scend, the rollers 11 travel along tracks T, and the counterweight beingcontrolled by members 1 and 8, also descends, and conversely when the bridge B descends, the counterweight W rises.

The position of the bridge and counterweight with its supporting and controlling mechanism, when the span is in its open position, is indicated by dotted lines in the figures. Slots 19 may be provided in pier A as shown in Fig. 1, and recesses 12 may be provided at both edges of the counter-.

weight as shown in Figs. 1 and 2, to afford clearance for the girders of the span B, when the bridge is in its open position.

The track T, may be supported in any suitable manner as by the pier A as shown in Fig. 1, or by structural members on said pier or by suitable connections to the girders of the approach span F The center of gravity G of'the counterweight YV, in Fig. 1, is approximately vertically over its supporting pivot 2 and it will be evident that the weight is prevented from rotation about pivot 2 and so falling over,

by the member or strut 8; for should said weight tend to fall or be forced by wind pressure away from the span B, it will be held by the member 8, which will press down on beam (land tend to rotate beam C about pivot 13, causing a downward pressure onrollers 11 which is resisted by the upward reaction of track T. Should the counter weight V, tend to fall towards the span B, the rollers 11 will tend to rise and are held from'so doing by the hold down rails 13, shown to larger scale in Fig. 3.

Having determined the position of the center of gravity 0. g. of the bridge and they total weight corresponding to said center of gravity and having chosen suitable locatlons for the various pivots and a suitable ratio for the weight of the counterweight, the path of the axle l0 and .shape of track .down tracks '13 are omitted.

T required to balance the bridge in all its positions may readily be determined, on the )rinci )le of virtual work b 1 sim ile ra )hic .7 l in methods.

The shape of the track T, which depends upon the relative positions of the various pivots and the axle 10, will be curved, in order to balance the span in all its positions, unless the positions of said points and said axle are suitably chosen, but when so chosen the track T may be made straight as shown in the drawings and an accuracy of balance attained well within the limits of'practice.

When the bridge is in its open position as shownin Fig. 1, should any force such as wind pressure be applied to the span tending to open it to a greater angle than that desired, the girders of the span B, will come into contact with the counterweight'VV, and

the span. counterweight and stabilizing mechanisms will become locked, the tendency to rotate about the pivot P, being resisted by the track T, through the beam C and link 8. 7

Referring to Fig. 3 the hold-down tracks 13 are shown as consisting of the flange angles of plate girders supported on the pier A and braced bysuita-ble brackets 14;

Fig. 4 shows an alternative construction whichmay be used in place of the rollers 11 and hold-down tracks 13. In the said Fig. 1, 15 is a slider mounted on the axle 10 of beam C and engaging bothtop and bottom surfaces of the flange of the specially shaped track T, the said track T being firmly at-,.100 tached to the pierA so as to resist any upward force onthe beam Flg. Fishows my invention applied to a bridge of the rolling type. In this figure the center of gravity G of the counterweight,

moment of the weightd/V, about its pivot 2,

will resist any possiblewind pressure tending to rotate the counterweight forward around said pivot 2 and hence no hold-down of the rollers 11 is necessary and the holdprovi'ded in the pier A in this figure to pr0- vide for clearance of the beam C, when the bridge is opened.

Fig. 6 shows my invention applied to a deck plate girder bridge, all the-mechanism except the counterweight and its supporting members 1 and 8 being below the roadway level. It will be noted that inthis figure the weight of the counterweight is carried mainly on member 8, and member 1 acts mainly as astabilizer and as in Fig. 5, the

" hold-down tracks 13 are not necessary and are omitted.

Fig. 7 shows another modification of my invention which the positions of, the pivot Slots 18, are 115 2 of the member 1 and the pivot 6 of the beam C coincide. On account of the coincidence of these two points the pivotal point 7 cannot be fixed directly to the counterweight W, but must have a motion with respect to it. I therefore attach the strut 8 to a slider 17, by the pivot 7, said slider bearing upon the faces of the member 1 and being free to move longitudinally on said member. In order to control the motion of the slider 17 on said member 1, I introduce an additional or auxiliary member 8, pivotally connected to said slider 17, at the point 7 and to the heel of the span B, at the point 9.

Hold down tracks or their equivalent may be required with the construction shown in this figure, but for the sake of clearness they have been omitted from the drawing.

In Figs. 5, 6 and 7, the operating mechanism has been omitted for clearness.

In Figs. 6 and 7, track T, is shown as supported on masonry wing walls 16 on pier A Slots 18 are preferably provided in said wall to avoid interference with the motion of beam C, likewise slots 19 may be provided in piers A, to avoid interference with the motion of the span.

I prefer to place pivots 2 and 6 on the line 0. g.-P prolonged, as shown in Figs. 1 and 5, also in the form shown in Fig. 6, I prefer to place pivot 6 on said line, as thereby the graphical constructions are simplified.

Various modifications of the general arrangements and details shown may be made without departing from the spirit of my invention, as for instance the roller 11, may be replaced by a sliding crosshead as shown in Fig. 4t, or the end of beam C, may be carried on a long link, the roller and tracks dispensed with, and other modifications will. readily suggest themselves.

Now, having described my invention, what I claim is:

1. In a bascule bridge the combination of a movable span having a rearwardly eX- tended end, a counterweight above said end and pivotally supported thereon, a beam pivoted to said end and movable therewith in a backward and forward direction and a strut pivotally connecting said counterweight and said beam.

2. In a bascule bridge, a movable span having a rearwardly extended end, a counterweight above said end and pivotally supported thereon, a beam pivoted to said end and movable therewith in a backward and forward direction, a roller supporting said beam on a fixed part of the bridge, and a strut pivotally connecting said counterweight and said beam.

3. In a bascule bridge, a movable span having a rearwardly extended end, a counterweight above said end, and pivotally supported thereon, a beam pivoted. to said end and movable therewith, a roller supporting said beam, a substai'ltially horizontal track supporting said roller and a strut pivotally connecting said counterweightand said beam.

4-. In a bascule bridge, a movable span having a rearwardly extended end, a counterweight above said end and pivotally supported thereon and stabilizing means pivoted to and horizontally movable with said end to hold said counterweight above said end during motion of said span.

5. In a bascule bridge, a movable span having a rearwardly extended end, a counterweight above said end and pivotally supported thereon and means pivoted to and backwardly and forwardly movable with said end to maintain said counterweight in a vertical position during motion of said span whereby said counterweight balances said span in all its positions.

6. In a bascule bridge, a rotatable span having a rearwardly extended end, a counterweight above said end, a counterweight pivot connecting said counterweight with said end on the line passing through the centres of gravity and rotation of said span, a beam pivoted to said end. a pivoted strut connecting said beam to said counterweight, a roller supporting said beam and a track on which said. roller moves backward and forward, whereby the center of gravity of said counterweight remains vertically over said counterweight pivot during motion of said span.

7. In a bascule bridge, a. movable span with girders having rearwardly extended ends, a counterweight above the roadway of said bridge, posts supporting said counterweight on said ends and pivoted thereto, beams pivoted to said ends and connected to said counterweight by pivoted struts, rollers supporting the ends of said beams, and substantially horizontal tracks supporting said rollers, said tracks adapted to maintain said counterweight in a vertical position over said ends during motion of said span.

8. In a bascule bridge, a movable span having a rearwardly extended end, a counterweight above said end, a counterweight pivot connecting said counterweight with said end on the line passing through the centers of gravity and rotation of said span, a beam pivoted to said end, a pivoted strut connecting said beam to said counterweight, a roller supporting said beam and an horizontal track on which said roller moves backward and forward whereby the line joining said counterweight pivot and the center of gravity of said counterweight remains substantially parallel to its original position during the motion of said span.

THOMAS E. BROWN, JR, 

